When perchlorate ingested can harm the thyroid, which regulates human's metabolism and development. Pregnant women, nursing mothers and infants are particularly sensitive.
Drinking water contamination at a Mendon school thought to cause be fireworks was caught by new testing required by the state for perchlorate, but other communities with pyrotechnics say they have taken precautions.
A year ago Massachusetts adopted the nation's strictest standard for perchlorate contamination, with a threshold of two parts per billion, or about 2.5 teaspoons in an olympic-sized swimming pool.
The chemical is used as an oxidizer in fireworks, ammunition and in explosives used for blasting in construction, said Ed Coletta, spokesman for the Massachusetts Department of Environmental Protection.
The danger comes when the chemical washes into drinking water supplies, Coletta said. When perchlorate ingested can harm the thyroid, which regulates human's metabolism and development. Pregnant women, nursing mothers and infants are particularly sensitive.
In Mendon, the Clough School used to host an annual carnival with a fireworks display on land next to the school. The carnival has not been held the past couple years.
``The places we have seen it previously are those with big displays sponsored by social clubs, towns, whoever,'' Coletta said. ``They material explodes and you have debris fall down and the pieces have the perchorlate on them. When it rains, the perchlorate is taken off the debris and goes into the ground where it can get into the ground water.''
Many communities around Eastern Massachusetts have fireworks displays, and many more had them in the recent past. Those who host the shows have been put on notice about the dangers of perchlorate.
Perchlorate contamination was discovered in wells supplied by Buckmaster Pond in Norwood, but it was below the state threshold. The pond is owned by Norwood and has been considered to be used as a backup water supply for the town. It actually sits in Westwood and used to be the site of Westwood's pyrotechnic show, which has since been moved elsewhere.
In Southborough, the annual fireworks show for Southborough Summer Nights was moved from a site next to the Sudbury Reservoir to a field next to Neary School, said Fire Chief John Mauro.
``We moved it because we were shooting right over the reservoir, which is a back-up water supply,'' Mauro said. ``We wanted to ensure we weren't near any back up water supplies.''
Other communities have shows, but in locales that do not affect water supplies.
Waltham has an annual display, but Mayor Jeannette McCarthy said the water supply is not threatened.
``We do it over the high school football field, so we don't really have any water in that area,'' McCarthy said.
Newton's Fourth of July celebration occurs each year at Albemarle Park. City spokesman Jeremy Solomon said city residents are not at risk because Newton does not rely on ground water.
``Our ground water is not used as drinking water. Ours comes from the MWRA,'' Solomon said. ``Any ground water would not be consumed, so we don't test the ground water for perchlorate.''
Fireworks became a hot issue in Northborough last year. The annual Applefest display takes place at Algonquin Regional High School. Some residents worried about perchlorate seeping into drinking water supplies, but Fire Chief David Durgin said he believes it is safe.
``It's a non-issue,'' Durgin said. ``We brought in environmental engineers, we had the fireworks people come out and took the information approved by the DEP. We beat this issue to death.''
The contamination found in Mendon is the latest found in the state, Coletta said. All public water supplies must be tested regularly - twice a year for wells and four times a year for surface water supplies, including rivers, lakes and reservoirs.
The standards apply to any public water supply, Coletta said, which includes a town or city, along with any system that serves at least 25 people for 65 days a year, or more.
``We are talking a school, a camp, offices,'' Coletta said. ``A lot of places.''
The culprit for the contamination often turns out to be fireworks, but other sources have been found around the Bay State, said Ray Raposa, executive director of the New England Water Works Association. The Holliston-based professional group works with water department workers and consultant working in the industry.
``One incident that occurred, where (the perchlorate issue) started in Massachusetts, it was found on Cape Cod around the old military installation,'' Raposa said. ``The ammunition was never really cleaned up, and (perchlorate) got washed into groundwater.''
Another instance occurred near Lowell on the Merrimack River, Raposa said. The source turned out to be a factory that was discharging it into the river.
If found, perchlorate contamination can be treated in a water treatment plant, Raposa said.
``The treatment technology is there,'' Raposa said. ``If they don't have a treatment plant they have to put it in. If they have one, it they could make some modifications.''
The other key to dealing with the contamination, Raposa said, is to remove the source of the pollution.
``In our part of the country it is not something that naturally occurs,'' Raposa said. ``It is more a byproduct of some human activity. It is important to move the activity away from the drinking water area, so doesn't have an impact.''
The DEP's Coletta said fireworks can still be used, but precautions should be taken.
``The best management practices for those is to pickup as much of the debris as possible,'' Coletta said.
Charlie Breitrose of The MetroWest Daily News (Framingham, Mass.) can be reached at 508-490-7461 or firstname.lastname@example.org.